The sprawling factory, barring an unlikely rise in demand, is expected to shut down completely by the end of next year.

Time is running out at Southern California's last major conventional aircraft factory.

Citing declining orders for its C-17 cargo planes, Boeing Co. said it was cutting 900 of the 3,700 jobs at its sprawling Long Beach plant. Barring congressional intervention or a spate of foreign orders — which analysts say is unlikely — the factory is expected to shut down completely by the end of next year.

"There's just not that much of a market for this aircraft," said Scott Hamilton, an aviation industry consultant in Issaquah, Wash.

The layoffs, which the company announced late Wednesday, continue the decline in local aerospace jobs. The industry, which employed more than 160,000 people in Southern California in 1990, had an estimated workforce of about 47,650 last year.

The C-17 Globemaster III, a massive, four-engine jet that hauls 60-ton tanks, troops and medical gear across continents and yet lands on short runways, has been in production since the early 1990s. The plant, next to Long Beach Airport, is a symbol of a bygone era in Southern California when factories ran around the clock building colossal aircraft.

"Our rich history of aerospace manufacturing makes this an emotional day for Long Beach, as the C-17 plant is the last of what was previously a robust aerospace manufacturing industry in California," Long Beach Mayor Bob Foster said.

Boeing once built the 717 jetliner in Long Beach. It was also where McDonnell Douglas manufactured the MD-80 commercial jet. Farther north, Lockheed Corp. produced the Constellation and Electra in Burbank. Now, those facilities have been shuttered.

In recent years, the industry has transformed from blue-collar manufacturing work to more white-collar engineering, concentrating on high-tech systems such as spy satellites, precision missiles and robotic planes. But this work doesn't need nearly as many people.

Newly laid-off workers will also face a tough hiring environment. Unemployment in California stands at 12.4%. In Los Angeles County, it is 12.9%. Workers were told about the layoffs Wednesday, and termination notices will begin to be issued Friday, the company said.

"There are a lot of people upset about it," said Ray Luciani, 60, a maintenance mechanic at the plant. "I'm just hoping to last three more years to get my pension."

The news comes on top of announcements last year from Boeing that it was cutting 800 jobs by relocating two other key defense programs from Long Beach. And Northrop Grumman Corp. announced it would eliminate 500 jobs in its aerospace division in El Segundo and Redondo Beach.

Northrop also announced it planned to move its headquarters to the Washington, D.C., area from Los Angeles, where the company has been since it was founded in 1939.

Last year, Boeing hinted that layoffs were ahead. In February it announced it was cutting production rates to 10 aircraft a year from 15 to draw out the assembly line's life.

"This is a very difficult decision, no doubt about it," said Bob Ciesla, C-17 program manager. "I know most of these folks, but it's necessary to extend the life of the line."

By this summer, assembly lines will slow down and result in the elimination of the second shift for the 23 remaining C-17s to be built.

Boeing said the Long Beach cuts would be part of the 1,100 C-17-related jobs being dropped nationwide. The Chicago-based company said it would provide assistance for affected workers seeking potential positions elsewhere within the company.

With tight Pentagon budgets, the Air Force stopped ordering C-17s in 2006. Since then, Congress has made last-minute earmarks to keep the plant rolling. Last year, lawmakers set aside funding for 10 new planes. Experts say congressional concerns about the budget deficit and federal spending this year may make continued C-17 funding from Washington doubtful.

Boeing has been pushing foreign sales as a way to help prolong the production line, but because these orders are small — about five planes at a time — they have not been enough to sustain the production line.

One of them — the sale of 10 C-17s to India — could help the line stay open an additional year. But selling to a foreign government is a complicated process in which the request must first pass muster with the State Department and Congress.

But Congress has continually come to the program's rescue because it supports roughly 25,000 supplier jobs in 44 states.

Boeing said that in California, about 14,000 jobs — many at small mom-and-pop machine shops — depend on the program.

"Boeing has been very successful at lobbying Congress on the program," said Hamilton, the aviation industry consultant. "It's likely that Boeing will turn to them again to keep this thing going."